This invention relates to dry spinning spandex yarns. More particularly, it relates to a spinneret for obtaining such a yarn.
Smith U.S. Pat. No. 3,094,374 and Hunt U.S. Pat. No. 3,428,711 describe methods for preparing coalesced spandex filaments. In a preferred embodiment described by Smith the yarns contain individual filaments which adhere to one another to form a unitary group of filaments. The Hunt patent which discloses a preferred process for making the filaments in Examples I and II is incorporated herein by reference.
The conventional spinnerets used for light denier spandex production have two rings, i.e., an outer ring and an inner ring of grouped orifices wherein each group is composed of four holes. The spacing between holes of each grouping is the same regardless of whether the group is in the inner or outer ring. The four filaments from each orifice group coalesce as they pass downwardly through the evaporative environment of the spinning cell to form a single end (individual threadline) which is wound onto its separate package. Thus, many individual packages are wound from the yarns issuing from a single spinneret and a single spinning cell.
Higher spinning productivity has been achieved by increasing the number of groups of filaments per spinning cell. The greater number of groups increases the frequency of filament migration between groups. Also, it has now been discovered that yarn ends spun from the inner rings of the spinneret orifice pattern have significantly different power levels from those spun from the outer rings. These end-to-end power differences cause undesirable streaks in fabrics for the following reason. In modern warping operations a plurality of individual yarn packages are placed into a creel and yarn ends are fed side-by-side therefrom onto a beam for shipment to the knitter. The knitter feeds each individual end to each juxtaposed needle of the knitting machine. Thus, each lengthwise wale of the knitted fabric will consist of a yarn end from a different yarn package. Differences of power between juxtaposed yarn ends cause significant differences in knitting tensions which cause undesirable streaks in fabrics.